Maxima Function
is (expr)
Attempts to determine whether the predicate expr
is provable from the facts in the assume database.
If the predicate is provably true or false,
is returns true or false, respectively.
Otherwise, the return value is governed by the global flag prederror.
When prederror is true,
is complains with an error message.
Otherwise, is returns unknown.
ev(expr, pred)
(which can be written expr, pred at the interactive prompt)
is equivalent to is(expr).
Examples:
is causes evaluation of predicates.
(%i1) %pi > %e; (%o1) %pi > %e (%i2) is (%pi > %e); (%o2) true
is attempts to derive predicates from the assume database.
(%i1) assume (a > b); (%o1) [a > b] (%i2) assume (b > c); (%o2) [b > c] (%i3) is (a < b); (%o3) false (%i4) is (a > c); (%o4) true (%i5) is (equal (a, c)); (%o5) false
If is can neither prove nor disprove a predicate from the assume database,
the global flag prederror governs the behavior of is.